Sintering apparatus



Nov, 20, 1923. v v 11,474,859

WLG.SWART S INTERING APPARATUS Filed Oct. 8, 1919 2 Sheetsheet 1 Ira/en???" W6 4 727? 6.5WHRT 'Nov. 20 1923. 1,474,859

. W. G. SWART SINTERING APPARATUS Filed Oct. 8, 1919 2 Sheets-Sheet 2 entire sintering operation, this suction be- Patented Nov. 2% 1923.

PATENT @FFHCE SINTERING APPARATUS.

Application filed October 8, 1919. Serial No. 329,314.

To all whom it may concern:

Be it known that I, WALTER G. SWART, a citizen of the United States, residin at Duluth, in the county of St. Louis and tate of Minnesota, have invented certain new and useful Improvements in Sintering Apparatus, of which the following is a specification.

This invention relates to improvements in sinterin apparatus and has for its-object new an useful improvements for sintering apparatus which may be operated more economically and efiicientlythan present day ap aratus.

n sintering hitherto in the continuous process it has been customary to pass the pans, or pallets, continuously over a suction compartment during substantially the ing maintained substantially constant. In the operation of the intermittent process, so-called because the pans, or .pallets, are intermittently sintered and then discharged,

ithas also been customary to'utilize a substantially uniform suction during the entire sintering operation. In both instances, this entails the operation of the suction pump, or fan, at or near its maximum load.

When a mass of ore and fuel is ignited at the top and begins to sinter, it is. usually in its best condition for good sintering results. After any portion of such mass has become sintered, it has lost its fuel and itsmoisture and becomes a porous coke-like mass, which allows air to pass much more freely than before the sintering action took place. It will, therefore, be obvious that whenever any given mass is being sintered, the amount of air passin through it steadily increases because of t e increasing porosity of the mass. If the amount of air used at the beginning of the re-action is just sufiicient, then there is an enormous excess of air passing through towards the end of the reaction. Not only does this excess of air do no good in the process itself, but it adds very greatly to the work done by the fan.

It is well known to those skilled in the art that other (xmditions being uniform, the powerrequired to operate a centrifugal suction fan, or the like, is approximately proportional to the amount of air which is passing through said fanfconsequently, in sintering, as the porosity of the mass increases, the power utilized by the fan will increase owing to the excess of air, although, the passage of this air through the sintering mass is a detriment rather than an advantage as stated above.

It is my object in this invention to provide apparatus in which the maximum suction may be applied at the beginning of the sintering operation and such suction be decreased as the sintering operation approaches its completion.

The means in which I accomplish these objects and others will be more fully set forth and described in the following specification andshown in the accompanying drawings in which: a

Figure 1 is a partially diagrammatic side elevation of apparatus embodying one form of my invention, as applied to present-day sintering apparatus;

Fig. 2 is a similar view showing a modification of my invention;

Fig. 3 is a plan view, showing diagrammatically m invention as applied to the process for intermittent sintering;

Fig. 4 is a modification showing my invention also applied to apparatus for intermittent sintering.

Like numerals refer to like elements throughout the drawings, in which, 10 designates sintering pallets mounted to move longitudinally upon suitable track work 11. Adjacent the left-hand end of the apparatus, which moves in the direction indicated by the arrow in Fig. 1, is a charging hopper 12 having its delivery end adjacent the pallets 10 and an igniting member 13 is located above the pallets to the right of the charging hopper 12. The pallets are charged from the hopper as they pass beneath, the charge, as is well-known, comprising a moist well-mixed mixture of powdered fuel and ore. This mixture is ignited at its upper surface by the igniter 13. A plurality of suction boxes 14, 15, and '16, which, in the form shown, are three in number, but which number may be varied to produce the desired results, are located beneath the path of travel of the pallets 10, the first suction box 14: being located beneaththe igniter 13. Pipes, or duets, 14:, 15, 16, lead from the suction boxes 14L, 15, and 16, respectively, to an exhaust fan 17 driven by an electric motor 18,01? the like. Suitable dampers, or valves 14:", 15", and 16", are located in the pipes 14L, 15 and 16,

till

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pipes when the fan 17 is in operation.

As the mixture of ore and fuel is ignited,

during its passage beneath the igniter 13,

passage of the zone of combustion through the pallets is efi'ected by thesuction in the suction boxes.

The damper 14! will normally be regulated to permit a relative maximum of suction to obtain in suction box 14, since during the passage of the pallets thereover, the sintering has progressed only a portion of the way through the pallet charges and a comparatively small amount of air is pass ing through such pallets since the porosity of the mass is mostly at the top. Suction 1n the suction box 15 will be reduced by the damper 15*, relative to that obtaining in box 14, since the zone of combustion has traveled farther and, consequently, there is greater permeability in the pallet charges and reduction of the suction results in the passage of less air through the sinter mass, or, to state the action otherwise, cutting down of the eifective flow by means of the valve 15 results in less air travelling through the mass and into the suction box 15, thereby permitting more thorough sintering and reducing the load upon the fan from what it would be were full flow of air possible through pipe 15*. Also, under normal conditions, the flow of air through the pipe 16 will be reduced below the rate of flow through, pipe 15 by suitable regulation of the VfllYflslG", since the zone of combustion is approaching its limit; i. e.,'the bottom of the pallet, and the porosity of the mass is such that the flow of air therethrough is much less impeded.

It will be apparent that if no means for regulating the flow of air through the pipes 14 15", and 16, were provided, the capacity of the fan 17 would have to be much larger than that required in the operation of my apparatus, since the increasing porosity of the mass as it travels over the successive suction boxes, would permit increasing flow of air and the tendency of such flow to follow the path of least resistance, would result in too great flow and interference with the 'proper sintering of the mass, while the suction obtaining in suction box 14 at the initiation of the ignition would be decreased resulting in imperfect sintering. This same detrimental eifect is present in the use of a single suction box where the porosity res'ultin from the sintering is frequently increase to such an extent that the sintering is imperfect and bodies of the unsintered mass are mixed with the sintered portions, the smtering being confined to the immediate neighborhood of the relatively large air ducts in the mass.

It will be obvious that in the embodiment shown in Fig. 1, the fiow of air from each of the suction boxes may be regulated, as described above, so that relatively eat suction and relatively small flow will present in box 14 during the early stage of sintering, while suction in box 15 may be reduced while obtaining the same, or slightly reater, flow and in box 16, the suction may be still furtherreduced and the flowthereby maintained constant or varied as desirable inthe treatment of different ores and mixtures.

By this regulation, the maximum efiiciency and economy of operation of the fan may be obtained, since it will not be necessary to employ a fan handling more air than is absolutely necessary for the proper sintering and the same may be run at a constant efiicient speed.

In Fig. 2, I have shown another embodiment of myinvention as applied to the continuous process, in which the same charging hopper 12 and igniter 13 are provided in con unction with the palletslO, but in lieu of the plurality of suction boxes, I provide a single suction box 20 extending beneath the pallets for a distance sufiicient to produce proper and thorou h SlIItGIiIIg'Of the charges on the pallets. for example, by the fan 17 and motor 18, as in the construction shown in Fig. 1. To decrease the flow of air as the sintering progresses, I provide a damper plate or cover 25, located above the surface of the pallets, being spaced from the top of the pallet at its forward end 25*, the space decreasing in the line of progress of the pallets toward the point at which sintering has been practically completed; the decrease in such spacing resulting in the gradual reduction of flow of air during the progress of the pallet charges as will be obvious. This apparatus accomplishes the same purpose as that shown in Fig. 1, but utilizes a difierent means as will be obvious.

In Fig. 3, I have shown my invention as applied to the intermittent, or stationary type of sintering apparatus in which stationary rows of suction boxes 30, 31', and 32, are provided, the suction boxes of each row being designated as 30, 30 30, 30, 31, 31, 31, 31, 32 32, 32, 32, respectively, as illustrated in the drawings. It is, of course, to be understood that a removable sintering pan of conventional type is to be mounted upon each of these suction boxes, the sintering of the mass in such pans being efi'ected by the suction of the respective boxes. Gates diagrammatically illustrated and designated by the numeral 35 connect each of the suction boxes with its adjacent neighbor so that one, or more, suction boxes of a row may be thrown into communication for a purpose to be described below.

A pluralit of exhaust fans A, B, C, and D, are provi ed, as shown, and ducts A B notion is obtained,

gamete 6,, and D jextend transversely of the rows tively.

30, 31, and .32, from each of said fans re spectively, such pipes, or ducts, terminating in communication with the suction boxesof the first row 30, being in communication with the suction boxes of rows 31 and 32' by branch pipes A B C and 1),, respec-- tively. Flow from the suction boxes through said pipes is regulated by means of the'valves A,, 13,, C and 1),, respec- By means of the apparatus just described, it is possible to throw the suction boxes of an row into communication with any of the fans, thereby preventing shutting down of the apparatus should one or more fans be thrown out of o eration. Furthermore, close regulation of t e sinterin in each an or each row of pans is 'possib e, as wil be obvious. Furthermore, the regulation. and determination of the proper size and speed of the fan is possible by the use of a battery of fans and suction boxes, as shown and described, and it is desirable in some instances to utilize a plurality of relatively small ca acity fans in lieu of one or more fans of re atively large capacity. The main ad vantage of this construction, however, consists in the fact that during the initial sta e of the sinterin proper suction may be tained in the ifierent suction boxes by the use of less than the entire battery of fans,

proper adjustment of thevalves and gates, ensuring communication of the difierent suction boxes with the fans which are in opera tion. As the porosity of the mass increases, the volume 0 air to be handled may increase and additional fans may be thrown into communication with the suction boxes to talze care of such increased flow, thereby permitting, during the entire sintering operation, the use of ans running at their maximum efliciency cutting in additional fans to compensate for the increased volume of air to be handled.

In -Fi 4, I have shown a plurality of suction xes 40, 41, and 42, and a corresponding number of suction fans 45, 4:6, and 4 ,respectively, and three pipes, or ducts, 50, 51, and 52, lead from the respective suction boxes. A cross-pipe, or duct, 60, extends between ducts and 52, its communication therewith being regulable by dampers and 60", respectively. This duct 60 passes beneath duct 51 but is in communication therewith by means of the valved duct 60*,the duct 60 being in communicationwith the fan 45,

the duct '61, similar to 60, also extends be tween ducts 50 and 52, the valves, or dampers, 61 and 61" controlling communication therewith and a valved duct 61, providing communication with the duct 5-1. The duct 61 is in communication with fan 46. A third cross duct 62, in communication with fan 47, provides a continuation of ducts 50 and 52, and duct 51 also terminates in communi-i'.

' boxes may be obtained by the use of a single fan operating at its most etlicient rate of speed. As in the case of the apparatus shown in Fig. 3, as the porosity of the sinter mass.

increases, a second fan may be thrown into this construction, it will be apparent communication with the suction boxes, while during the final stages of sintering the third fan may be cut in and eachot the boxes operated on a separate fan, by proper regulation ofthe valves and dampers. This construction also permits the use of the apparatus even'though one of the fans should break down, when such fan may be cut out of communication with the suction boxes, and the latter thrown into communication with the remaining fans.

It will be obvious that sintering may be regulated throughout the entire process by regulation of the flow of air through the mass overcoming the defects present in connection with the operation of present-day apparatus. lit will also be obvious that my invention is susceptible of numerous m'odi- 'fications and improvements and it do not wish to be restricted to the form shown, except as defined in the appended claims.

What I claim is:

1. In an apparatus of the class described, a plurality of travelling charge carrying members, draft creating means to circulate combustion sup ortin air through the charges on sai mem ers, and means to gradually reduce such draft during the travel of said members.

2. In apparatus of the class described, travellingl pallets, a suction box located adjacent t ei'eto, air-exhausting means in communication with said suction box, means to vary the flow or air through the charge carried by each pallet during the progress thereof over said suction box.

3. In apparatus of the class described, travelling pallets, a suction box located adjacent thereto, air-exhausting means in communication with said suction box, and means and to vary the flow of air through a charge carsaid pallets during the progress jacent thereto, air-exhausting means in communication with said suction box, and means to vary the flow of air through a charge earover said suction box, said means ried by said pallets duringthe progress therethe surface thereof and thereafter subject-. 10 of over said suction box, sald means coming the same 'to a draft to circulate comprising a plate located adjacent said pallets, bustion supporting gas, through the body, said plate being spaced 9, distance from said and decreasing such draft as combustion 5 pallets decreasing in the direction of moveprogresses. ment of the latter. y 'In testimony whereof, I have subscribed 16 5. A method of sintering ore consisting my name. 1

in depositing a body of ore and fuel in a suitable receptacle, igniting such body at WALTER G. SWART. 

